KR20080032347A - Backlight unit and liquid crystal display device having the same - Google Patents

Abstract

A backlight unit and an LCD(Liquid Crystal Display) including the same are provided to enable a thin light guide member disposed in the rear of an LC panel to distribute light uniformly, supplied from a light source unit, to the LC panel, thereby providing uniform luminance distribution. An LCD(Liquid Crystal Display) comprises an LC panel, a light guide member(420), and a light source unit(430). The light guide member is disposed in the rear of the LC panel. The thickness of the light guide member is about 0.2 to 0.6mm. The light source unit is disposed in one side of the light guide member. The light guide member includes an upper surface(420a) facing the LC panel, and a lower surface(420b) facing the upper surface. On the upper surface of the light guide member, an embossed prism pattern(421) is formed. On the lower surface of the light guide member, a depressed prism pattern(422) is formed. The embossed prism pattern is prolonged in a horizontal direction of a prolongation direction of the depressed prism pattern.

Description

BACKLIGHT UNIT AND LIQUID CRYSTAL DISPLAY DEVICE HAVING THE SAME}

1 is an exploded perspective view of a liquid crystal display according to a first embodiment of the present invention;

2 is a view for explaining a light guide member according to a first embodiment of the present invention;

3 is an enlarged view of a portion A of FIG. 2;

4 is an enlarged view of a portion B of FIG. 2;

5 is a graph for explaining the height change of the intaglio prism pattern of the light guide member according to the first embodiment of the present invention;

6 is a graph for explaining a pitch change of the intaglio prism pattern of the light guide member according to the first embodiment of the present invention;

7 and 8 are graphs of the experimental data obtained by varying the shape of the light guide member in the luminance distribution according to the distance from the light source,

9 is a view for explaining the effect of the present invention,

10 is a view for explaining a light guide member according to a second embodiment of the present invention;

11 is a view for explaining a light guide member according to a third exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: liquid crystal panel 200: driver

300: mold frame 400: backlight unit

420: light guide member 421: embossed prism pattern

422: engraved prism pattern 430: light source

500: lower cover 600: upper cover

The present invention relates to a backlight unit and a liquid crystal display including the same, and more particularly, to a backlight unit including a thin light guide member and a liquid crystal display including the same.

Recently, a flat panel display such as a liquid crystal display (LCD), a plasma display panel (PDP), or an organic light emitting diode (OLED) has been developed in place of the conventional CRT. Among them, the liquid crystal display device includes a liquid crystal panel constituting a screen and a backlight unit for supplying light to the liquid crystal panel because it is a non-light emitting device that cannot generate light by itself.

The backlight unit is divided into an edge type and a direct type according to the position of the light source unit. The edge type is a structure in which a light source is disposed on the side of the light guide plate, and is mainly applied to a relatively small liquid crystal display device such as a laptop type and a notebook computer. Such an edge type backlight unit has a good light uniformity, a long service life, and is advantageous for slimming a liquid crystal display device.

The edge type backlight unit includes a light source member that supplies light and a light guide member that uniformly distributes the light supplied from the light source unit in the liquid crystal panel direction.

Recently, thinner liquid crystal displays are preferred. However, the thickness of the light guide member has a thick problem.

However, when the thickness of the light guide member is reduced, a problem arises in that light supplied from the light source unit is not uniformly supplied in the direction of the liquid crystal panel.

Accordingly, an object of the present invention is to provide a backlight unit having a thin thickness and uniform luminance, and a liquid crystal display device including the same.

An object of the present invention is a liquid crystal display device, comprising a liquid crystal panel, a light guide member disposed behind the liquid crystal panel and having a thickness of 0.2mm to 0.6mm, and a light source unit disposed on one side of the light guide member. The member includes an upper surface facing the liquid crystal panel and a lower surface facing the upper surface, an embossed prism pattern is formed on the upper surface of the light guide member, an intaglio prism pattern is formed on the lower surface of the light guide member, and the embossed prism pattern is an engraved prism It can be achieved by the liquid crystal display device extending in the transverse direction of the pattern extending direction.

The thickness of the light guide member may be substantially 0.5 mm.

The light source unit may be disposed in the first direction, and an extension direction of the intaglio prism pattern may be parallel to the first direction.

The angle of the peak portion of the embossed prism pattern may be 90 degrees to 110 degrees.

The angle of the peak portion of the intaglio prism pattern may be 80 degrees to 85 degrees.

The height of the intaglio prism pattern may increase as the distance from the light source.

The height of the intaglio prism pattern may be proportional to the square of the distance from the light source unit.

The height of the intaglio prism pattern may be 1 μm to 8 μm.

The pitch of the intaglio prism pattern may decrease with distance from the light source.

The pitch of the intaglio prism pattern may be inversely proportional to the square of the distance from the light source portion.

The pitch of the intaglio prism pattern may be 50 μm to 200 μm.

The light source unit may include a light emitting diode.

Another object of the present invention is a backlight unit, comprising a light guide member having a thickness of 0.2mm to 0.6mm, and a light source unit disposed on one side of the light guide member, wherein the light guide member includes an upper surface and a lower surface facing the upper surface. An embossed prism pattern is formed on the upper surface of the light guide member, and an embossed prism pattern is formed on the lower surface of the light guide member, and the embossed prism pattern is achieved by the backlight unit extending in the horizontal direction in the extending direction of the engraved prism pattern. Can be.

The thickness of the light guide member may be substantially 0.5 mm.

The light source unit may be disposed in a first direction, and an extension direction of the intaglio prism pattern may be parallel to the first direction.

The angle of the peak portion of the embossed prism pattern may be 90 degrees to 110 degrees.

The angle of the peak portion of the intaglio prism pattern may be 80 degrees to 85 degrees.

The height of the intaglio prism pattern may increase as the distance from the light source.

The height of the intaglio prism pattern may be proportional to the square of the distance from the light source unit.

The height of the intaglio prism pattern may be 1 μm to 8 μm.

The pitch of the intaglio prism pattern may decrease with distance from the light source.

The pitch of the intaglio prism pattern may be inversely proportional to the square of the distance from the light source portion.

The pitch of the intaglio prism pattern may be 50 μm to 200 μm.

The light source unit may include a light emitting diode.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

A liquid crystal display device 1 according to an exemplary embodiment of the present invention will be described with reference to FIGS. 1 to 6.

As shown in FIG. 1, the liquid crystal display device 1 according to an exemplary embodiment of the present invention includes a liquid crystal panel 100 for forming an image, a driver 200 for driving the liquid crystal panel 100, and a liquid crystal. A mold frame 300 supporting the side of the panel 100, a backlight unit 400 for supplying light to the rear surface of the liquid crystal panel 100, a lower cover 500 for accommodating the backlight unit 400, The upper cover 600 is coupled to the lower cover 500 to cover the front surface of the liquid crystal panel 100.

The liquid crystal panel 100 is injected between the thin film transistor substrate 110, the color filter substrate 120 attached to face the thin film transistor substrate 110, and the thin film transistor substrate 110 and the color filter substrate 120. It includes a liquid crystal (not shown). The liquid crystal (not shown) is injected between the thin film transistor substrate 110 and the color filter substrate 120 and then sealed. The liquid crystal panel 100 is arranged in a matrix form of the liquid crystal cells forming a pixel unit, and forms an image by adjusting the light transmittance of the liquid crystal cells according to the image signal information transmitted from the driver 200.

In the thin film transistor substrate 110, a plurality of gate lines and a plurality of data lines are formed in a matrix form, and pixel electrodes and thin film transistors (TFTs) are formed at intersections of the gate lines and the data lines. The signal voltage applied through the thin film transistor is supplied to the liquid crystal (not shown) by the pixel electrode, and the liquid crystal (not shown) is aligned according to the signal voltage to determine the light transmittance.

The color filter substrate 120 includes a common filter made of a color filter made of RGB pixels through which light passes and a predetermined color, and a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). . The color filter substrate 120 has a smaller area than the thin film transistor substrate 110.

A portion where the color filter substrate 120 and the thin film transistor substrate 110 overlap each other is a display area of the liquid crystal panel 100, and a peripheral area of the non-overlapping display area is a non-display area of the liquid crystal panel. The driving unit 200 for applying a driving signal is provided on the side of the liquid crystal panel 100.

The driving unit 200 includes a flexible printed circuit board (FPC) 210, a driving chip 220 mounted on the flexible printed circuit board 210, and a circuit board connected to the other side of the flexible printed circuit board 210. 230). The illustrated driving unit 200 represents a method of a chip on film (COF), and other known methods such as a taper carrier package (TCP) and a chip on glass (COG) may be used. In addition, a part of the driver 200 may be mounted on the thin film transistor substrate 110.

The mold frame 300 is formed along the side of the liquid crystal panel 100, has a substantially rectangular shape, and supports the liquid crystal panel 100 spaced apart from the backlight unit 400.

The backlight unit 400 is disposed on the rear surface of the liquid crystal panel 100 and includes an optical member 410, a light guide member 420, a light source 430, and a reflective sheet 440.

The optical member 410 is disposed on the rear surface of the liquid crystal panel 100 and includes a diffusion sheet 411, a prism sheet 413, and a protective sheet 415. Here, the diffusion sheet 411 is composed of a base plate and a bead-shaped coating layer formed on the base plate. The diffusion sheet 411 serves to diffuse the light from the light source unit 430 and supply the light to the liquid crystal panel 100.

The prism sheet 413 has a triangular prism-shaped prism formed on the upper surface thereof in a predetermined arrangement. The prism sheet 413 collects the light diffused from the diffusion sheet 411 in a direction perpendicular to the plane of the upper liquid crystal panel 100. Two prism sheets 413 are generally used, and the micro prisms formed on each prism sheet 413 form an angle. The light passing through the prism sheet 413 proceeds almost vertically to provide a uniform luminance distribution.

The uppermost protective sheet 415 protects the prism sheet 413 that is weak to scratches. The light guide member 420 which guides light to the rear surface of the prism sheet 413 is disposed on the rear surface of the prism sheet 413.

The light guide member 420 is disposed at the rear of the liquid crystal panel 100, and serves to evenly distribute the light supplied from the light source unit 430 in the direction of the liquid crystal panel 100.

As shown in FIG. 2, the light source unit 430 is disposed at one side of the light guide member 420 in the first direction, and the thickness d ₁ of the light guide member 420 is substantially 0.5 mm. Meanwhile, in another embodiment, the thickness d ₁ of the light guide member 420 may be 0.2 mm to 0.6 mm.

The light guide member 420 includes an upper surface 420a facing the liquid crystal panel 100 and a lower surface 420b facing the upper surface 420a. An embossed prism pattern 421 is formed on the top surface 420a of the light guide member 420, and an intaglio prism pattern 422 is formed on the bottom surface 420b of the light guide member 420.

The embossed prism pattern 421 extends in a second direction that is horizontal in the first direction and is formed in an embossed prism shape having a predetermined height and a predetermined pitch.

As shown in FIG. 3, the angle θ ₁ of the peak portion 421a of the relief prism pattern 421 is 90 to 110 degrees.

The intaglio prism pattern 422 extends in parallel with the first direction and is formed in an intaglio prism shape having a variable height and a variable pitch.

As shown in FIG. 4, the angle θ ₂ of the peak portion 422a of the intaglio prism pattern 422 is 80 degrees to 85 degrees. Substantially, the angle θ ₂ of the peak portion 422a of the intaglio prism pattern 422 may be 83 degrees. The height d ₂ of the intaglio prism pattern 422 increases as the distance from the light source 430 increases. The height d ₂ of the intaglio prism pattern 422 is proportional to the square of the distance x from the light source unit 430, as shown in FIG. 5. Here, the x-axis of FIG. 5 is the distance x from the light source 430 and the y-axis is the height d ₂ of the intaglio prism pattern 422. The height d ₂ of the intaglio prism pattern 422 is 1 μm to 8 μm.

The pitch d ₃ of the intaglio prism pattern 422 decreases away from the light source 430. The pitch d ₃ of the intaglio prism pattern 422 is inversely proportional to the square of the distance x from the light source 430, as shown in FIG. 6. Here, the x-axis of FIG. 6 is a distance x from the light source unit 430 and the y-axis is a pitch d ₃ of the intaglio prism pattern 422. The pitch d ₃ of the intaglio prism pattern 422 is 50 μm to 200 μm.

The light source unit 430 is disposed in a first direction on one side of the light guide member 420. The light source unit 430 supplies light toward the light guide member 420. The light source unit 430 includes a light emitting diode. The reflective sheet 440 is disposed behind the light source 430.

The reflective sheet 440 is positioned between the light source unit 430 and the lower cover 500 to reflect the light of the light source unit 430 and to supply the light toward the light guide member 420.

The lower cover 500 is disposed at the rear of the reflective sheet 440 and serves to accommodate the backlight unit 400.

The upper cover 600 has a display window to expose the effective surface of the liquid crystal panel 100 to the outside, and is coupled to the lower cover 500.

The shape and length of the embossed prism pattern 421 and the intaglio prism pattern 422 were obtained through the following experiments. It looks at the experiment below.

Experimental results will be described with reference to FIGS. 7 to 8.

FIG. 7 is a graph showing the luminance of the liquid crystal display device according to the distance from the light source unit 430 when the shapes of the relief prism pattern 421 and the relief prism pattern 422 of the light guide member 420 are variable. As shown in FIG. 7, the x-axis represents a distance from the light source unit 430, and the y-axis represents luminance.

(a) The angle θ ₁ of the peak portion 421a of the embossed prism pattern 421 is substantially 105 degrees, and the height d ₂ of the engraved prism pattern 422 is 1 μm to 8 μm, the pitch (d ₃₎ of the prism pattern 422 represents a one time 50㎛ to 200㎛.

(b) the angle θ ₁ of the peak portion 421a of the embossed prism pattern 421 is substantially 105 degrees, and the height d ₂ of the engraved prism pattern 422 is 1 μm to 10 μm, the pitch (d ₃₎ of the prism pattern 422 represents a one time 50㎛ to 200㎛.

(c) the angle θ ₁ of the peak portion 421a of the embossed prism pattern 421 is substantially 105 degrees, and the height d ₂ of the engraved prism pattern 422 is 1 μm to 6 μm, the pitch (d ₃₎ of the prism pattern 422 represents a one time 50㎛ to 200㎛.

(d) The angle θ ₁ of the peak portion 421a of the relief prism pattern 421 is substantially 105 degrees, and the height d ₂ of the relief prism pattern 422 is 1 μm to 6 μm, the pitch (d ₃₎ of the prism pattern 422 represents a one time 50㎛ to 200㎛.

(e) the angle θ ₁ of the peak portion 421a of the embossed prism pattern 421 is substantially 105 degrees, and the height d ₂ of the engraved prism pattern 422 is 1 μm to 8 μm, The pitch d ₃ of the prism pattern 422 is 50 μm to 200 μm, and the height d ₂ of the negative prism pattern 422 is proportional to the cube of the distance from the light source 430, and the negative prism pattern 422. The pitch d ₃ ) is in inverse proportion to the cube of the distance from the light source 430.

Comparing (a), (b) and (c), the brightness of (a) is high and uniform. Accordingly, the height d ₂ of the intaglio prism pattern 422 is preferably 1 μm to 8 μm.

Comparing (c) and (d), it can be seen that there is little difference in luminance between (c) and (d). Accordingly, the angle θ ₁ of the peak portion 421a of the relief prism pattern 421 is preferably 90 degrees to 110 degrees.

Comparing (d) and (e), it can be seen that the luminance of (d) is high and uniform. Accordingly, the height d ₂ of the intaglio prism pattern 422 is proportional to the square of the distance from the light source 430, and the pitch d ₃ of the intaglio prism pattern 422 is the square of the distance from the light source 430. It is desirable to be inversely proportional to.

FIG. 8 shows that the angle of the peak portion 422b of the intaglio prism pattern 422 of the light guide member 420 is substantially 83 degrees, and the pitch d ₃ of the intaglio prism pattern 422 is substantially 200 μm, and is embossed. When the angle of the peak portion 421b of the prism pattern 421 is variable, it is a graph showing the luminance of the liquid crystal display device according to the distance from the light source unit 430. As shown in FIG. 8, the x-axis represents the distance from the light source unit 430, and the y-axis represents the luminance. (I), (II) and (III) represent positions corresponding to (I), (II) and (III) of FIG. 7, respectively.

(f) shows when the angle θ ₁ of the peak portion 421a of the relief prism pattern 421 is substantially 85 degrees.

(g) shows when the angle θ ₁ of the peak portion 421a of the relief prism pattern 421 is substantially 90 degrees.

(h) shows when the angle θ ₁ of the peak portion 421a of the relief prism pattern 421 is substantially 95 degrees.

(i) shows when the angle θ ₁ of the peak portion 421a of the relief prism pattern 421 is substantially 100 degrees.

(j) shows when the angle θ ₁ of the peak portion 421a of the relief prism pattern 421 is substantially 105 degrees.

(k) indicates when the angle θ ₁ of the peak portion 421a of the relief prism pattern 421 is substantially 110 degrees.

Comparing (f) to (k), it can be seen that (g) to (k) has higher luminance and uniformity than (f). Accordingly, the angle θ ₁ of the peak portion 421a of the embossed prism pattern 421 is preferably 90 degrees to 110 degrees.

9, the effect of the present invention will be described.

9 shows the luminance of the liquid crystal display according to the present invention when the viewing angle varies depending on the distance from the light source 430.

As shown in FIG. 9, the x axis represents a viewing angle and the y axis represents luminance. (l), (m) and (n) represent portions corresponding to (I), (II) and (III) of FIG. 7, respectively, and (o) represents (l), (m) and (n) of The average value is shown.

Since variations in luminance between (l), (m), and (n) are small, it can be seen that the luminance of the liquid crystal display device according to the present invention is uniform.

Hereinafter, a second embodiment and a third embodiment according to the present invention will be described with reference to FIGS. 10 and 11.

Hereinafter, only the characteristic parts distinguished from the first embodiment will be described and described, and the descriptions omitted will be in accordance with the first embodiment and known techniques. Incidentally, in the second and third embodiments of the present invention, for the convenience of description, the same components will be described using the same reference numerals.

As shown in FIG. 10, in the light guide member 420 according to the second embodiment of the present invention, the light source 430 is disposed on both side surfaces of the light guide member 420. The pitch p ₁ of the intaglio prism pattern 422 of the light guiding member 420 decreases away from the light source 430 and is the smallest in the middle of the light guiding member 420.

As illustrated in FIG. 11, in the light guide member 420 according to the third embodiment of the present invention, a light source unit 430 is disposed on one side of the light guide member 420. The pitch p ₂ of the intaglio prism pattern 422 of the light guide member 420 is constant.

As described above, according to the present invention, a backlight unit having a thin thickness and uniform luminance and a liquid crystal display device including the same are provided.

Claims (24)

In the liquid crystal display device, A liquid crystal panel; A light guide member disposed behind the liquid crystal panel and having a thickness of 0.2 mm to 0.6 mm; It includes a light source unit disposed on one side of the light guide member, The light guide member includes an upper surface facing the liquid crystal panel and a lower surface facing the upper surface, An embossed prism pattern is formed on an upper surface of the light guide member, and an intaglio prism pattern is formed on a lower surface of the light guide member. And the embossed prism pattern extends in a horizontal direction of an extension direction of the engraved prism pattern. The method of claim 1, And the thickness of the light guide member is substantially 0.5 mm. The method of claim 1, The light source unit is disposed in a first direction, and an extension direction of the intaglio prism pattern is parallel to the first direction. The method of claim 1, The angle of the peak portion of the embossed prism pattern is 90 to 110 degrees. The method of claim 1, The angle of the peak portion of the intaglio prism pattern is 80 to 85 degrees characterized in that the liquid crystal display device. The method according to any one of claims 1 to 5, And the height of the intaglio prism pattern increases as the distance from the light source unit increases. The method of claim 6, And the height of the intaglio prism pattern is proportional to the square of the distance from the light source unit. The method of claim 7, wherein Liquid crystal table market value, characterized in that the height of the intaglio prism pattern is 1㎛ to 8㎛. The method of claim 6, The pitch of the intaglio prism pattern is reduced as the distance from the light source unit. The method of claim 9, And the pitch of the intaglio prism pattern is inversely proportional to the square of the distance from the light source unit. The method of claim 10, The pitch of the intaglio prism pattern is a liquid crystal display, characterized in that 50㎛ to 200㎛. The method of claim 1, The light source unit includes a light emitting diode. In the backlight unit, A light guide member having a thickness of 0.2 mm to 0.6 mm; It includes a light source unit disposed on one side of the light guide member, The light guide member includes an upper surface and a lower surface facing the upper surface, An embossed prism pattern is formed on an upper surface of the light guide member, and an intaglio prism pattern is formed on a lower surface of the light guide member. The embossed prism pattern is a backlight unit, characterized in that extending in the horizontal direction of the extending direction of the intaglio prism pattern. The method of claim 13, And a thickness of the light guide member is substantially 0.5 mm. The method of claim 13, The light source unit is disposed in a first direction, and the extension direction of the intaglio prism pattern is parallel to the first direction. The method of claim 13, The angle of the peak portion of the embossed prism pattern is a backlight unit, characterized in that 90 to 110 degrees. The method of claim 13, The angle of the peak portion of the negative prism pattern is a backlight unit, characterized in that 80 to 85 degrees. The method according to any one of claims 13 to 17, And a height of the intaglio prism pattern increases as the distance from the light source is increased. The method of claim 18, And the height of the intaglio prism pattern is proportional to the square of the distance from the light source unit. The method of claim 19, The height of the intaglio prism pattern is a backlight unit, characterized in that 1㎛ to 8㎛. The method of claim 18, And a pitch of the intaglio prism pattern decreases away from the light source. The method of claim 21, The pitch of the intaglio prism pattern is inversely proportional to the square of the distance from the light source unit. The method of claim 22, The pitch of the intaglio prism pattern is a backlight unit, characterized in that 50㎛ to 200㎛. The method of claim 13, And the light source unit comprises a light emitting diode.

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